The present invention relates to an arrangement on transfer drums for in-register sheet transfer in sheet rotary printing machines with gripper units which are mounted on cylinders and additionally arranged toothed segments which are in engagement during the sheet transfer.
Toothed segments on transfer drums are known. German document DE-AS 1,033,681 discloses a sheet transfer drum with such devices. In this device a known toothed rim with a springy toothed segment is arranged on the shaft of the transfer drum and engages with a drive wheel of the subsequent transfer drum and in addition a fixed toothed segment is provided. The fixed toothed segment cooperates only during the sheet transfer with an identical toothed segment mounted on the drive toothed rim of the preceding transfer drum. The springy toothed segment is axially offset relative to the fixed toothed segment. Due to this arrangement the registering device, during the sheet transfer in the event of a differences in registry, turns the drive wheel and thereby the transfer drum by the registry difference.
This device has the disadvantage that in the event of registry difference the drive wheel and thereby the transfer drum must be turned by the same difference. For turning these bodies which have great masses considerable tangential forces are needed, which lead to a premature wear of the toothed segments.